Life cycle assessment of a novel blast furnace slag utilization system

A novel system was proposed to realize the high value-added utilization of blast furnace slag. In this study, a comprehensive analysis concerning energy consumption, environmental impact and economic cost of the system was conducted based on the perspective of life cycle. Considering the serious situation of global warming, CO2 emission cost was also included. Main contributors in terms of environmental impact, energy consumption and economic cost were traced through contribution analysis. Global warming potential was the most prominent environmental issue (contributing 65.71% to total impact) and material cost offered the largest economic burden (contributing 90.57% to total cost). However, the adsorption capacity of two products offset total CO2 emission to −6103.62 kg·tslag−1 and decreased total economic cost to 352.26 $·tslag−1, turning the major limitation into a great opportunity. Most energy was consumed in upstream production of chemicals and only 3.18% of the total energy consumption came from the downstream utilization process. According to the sustainability evaluation among three processes, pretreatment performed worst and the hydrotalcite-like compounds synthesis process best. Additionally, sensitivity analysis indicated that overall performance of the system could be efficiently improved by reducing hydrochloric acid consumption. Analysis results in this study exhibited the huge potential of the system in emission reduction and could provide guidance for further improvement. •Life cycle assessment was conducted for the novel blast furnace slag utilization system.•Two kinds of high value-added products of zeolite and hydrotalcite-like compounds were synthesized simultaneously.•The net CO2 emission was −6103.62 kg·tslag−1 and the economic cost was decreased by 250.80 $·tslag−1.•The weaknesses of unit processes in sustainability performance were identified by normalization.